The following is a summary of “External validation of the alternative Ankylosing Spondylitis Disease Activity Score in three randomized clinical trials of ixekizumab,” published in the June 2023 issue of Rheumatology by Ortolan, et al.
For a study, researchers sought to evaluate the truth and discrimination aspects of the alternative Ankylosing Spondylitis Disease Activity Score (altASDAS) in an external cohort, as per the OMERACT filter 2.0. The altASDAS was designed to be used when patient global assessment (PGA) is not available.
The study pooled cohorts from the COAST trials of ixekizumab (COAST-V, -W, -X; 16-week primary endpoint), which included patients with radiographic/non-radiographic axial spondyloarthritis (SpA) and had a 16-week primary endpoint. The ASDAS (original formula with PGA) and altASDAS were calculated for each patient. The truth was assessed by comparing altASDAS with continuous ASDAS using intraclass correlation coefficients (ICCs) and ASDAS disease activity (DA) states using weighted κ. Bland–Altman plots were used to assess mean difference (MD) and 95% limits of agreement (LoA) between altASDAS and ASDAS. Pearson’s correlations were calculated between altASDAS/ASDAS and other relevant constructs to assess agreement. Discrimination was tested by evaluating the ability of altASDAS to distinguish between high and low disease activity based on nocturnal pain >6/10, which served as an external anchor. Agreement (κ) with ASDAS in major improvement (MI) and clinically important improvement (CII) was also assessed.
The study included 958 patients. The altASDAS showed very good agreement with ASDAS (ICC = 0.99, κ = 0.91). The mean difference between altASDAS and ASDAS was 0.03 (95% LoA -0.31–0.24), and correlation coefficients between altASDAS and related constructs fell within a prespecified 0.3-wide band around those between ASDAS and the same constructs. In terms of discrimination, the altASDAS effectively distinguished between disease activity states and demonstrated agreement with ASDAS response (κ MI = 0.91, CII = 0.93).
The altASDAS had been validated as a truthful and discriminative index in an external cohort, making it a reliable alternative for cases where patient global assessment (PGA) was unavailable.
Source: academic.oup.com/rheumatology/article-abstract/62/6/2257/6772504?redirectedFrom=fulltext